buildMix: default to removing target config (#430275)

  meta ? { },

  enableDebugInfo ? false,

  mixEnv ? "prod",

  removeConfig ? true,

  # A config directory that is considered for all the dependencies of an app, typically in $src/config/

  # This was initially added, as some of Mobilizon's dependencies need to access the config at build time.

  appConfigPath ? null,

  ...

}@attrs:

assert appConfigPath != null -> removeConfig;

let

  shell =

    drv:

            runHook preConfigure

            ${./mix-configure-hook.sh}

            ${lib.optionalString (removeConfig && isNull appConfigPath)

              # By default, we don't want to include whatever config a dependency brings; per

              # https://hexdocs.pm/elixir/main/Config.html, config is application specific.

              ''

                rm -rf config

                mkdir config

              ''

            }

            ${lib.optionalString (!isNull appConfigPath)

              # Due to https://hexdocs.pm/elixir/main/Config.html the config directory

              # of a library seems to be not considered, as config is always

              # application specific. So we can safely delete it.

              # Some more tightly-coupled dependencies do depend on the config of the application

              # they're being built for.

              ''

                rm -rf config

                cp -r ${appConfigPath} config